Berlin 2015 – scientific programme

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KR: Fachgruppe Kristallographie

KR 7: Optical and Nonlinear Optical Properties II (DF jointly with KR)

KR 7.5: Talk

Wednesday, March 18, 2015, 16:00–16:20, EB 407

Extended ab-initio study of the LiNbO₃ band gap — •Arthur Riefer, Simone Sanna, and Wolf Gero Schmidt — Theoretische Physik, Universität Paderborn, 33098 Paderborn

Lithium niobate (LiNbO₃) is one of the most important ferroelectric materials and the most important nonlinear optical material. The electronic and optical properties of LiNbO₃ have been studied in recent years with ab-initio methods [1-4] within high accuracy indicating good agreement with experimental results. However, measurements by Redfield et al. [5] show a temperature dependence of the band gap, which can be traced back to different effects. In order to model the temperature dependence of the electronic band gap, we have extended the approaches described in Refs. [1-4] under two aspects. On the one hand, hybrid functionals are employed to provide improved starting points for many-body perturbation theory, which is applied to study the electronic properties. On the other hand, the influence of the temperature on the LiNbO₃ band gap is investigated by means of molecular dynamics simulations. The results are compared with former works and experimental findings.

[1] W. G. Schmidt et al., Phys. Rev. B 77, 035106 (2008)

[2] C. Thierfelder et al., phys. stat. sol. (c) 7, 362 (2010)

[3] A. Riefer et al., IEEE Trans. on Ultrasonics, Ferroelectrics and Frequency Control 59, 1929 (2012).

[4] A. Riefer et al., Phys. Rev. B. 87, 195208 (2013)

[5] Redfield et al., J. Appl. Phys. 45, 10, (1974)